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Mammary Cancer in Female Dogs: Symptoms, Treatment & Prevention
Breast Cancer, Mammary Gland Tumor, MGT
SUMMARY OF CONTENT
SEVERITY:
- Requires a diagnosis by a veterinarian
- May resolve within weeks after surgery if caught early
- May be treatable by a veterinarian
- Spaying female dogs before their first heat cycle reduces the risk of mammary cancer to less then 1%, however, spaying prior to their second heat cycle still greatly reduces their risk of developing mammary cancer compared to those spayed later.
- Transmission is not possible between animals and not possible between animals and people
- Diagnosis requires physical exam, fine needle aspirate and cytology, x-rays
VERY COMMON IN
Symptoms & Signs
Mammary tumors are observed as a solid mass or as multiple swellings underneath the belly. When tumors do arise in the mammary tissue, they are usually easy to detect by gently palpating the mammary glands. When tumors first appear, they may feel like small pieces of pea gravel just under the skin. They can grow rapidly in a short period of time and may double their size every month or so. The dog normally has five pairs of mammary glands. Although mammary cancer can occur in any of the glands, it is more common in the 4th and 5th glands (closest to the hind limbs). The only way to confirm if a tumor is malignant or benign is through diagnostics done by your veterinarian.
The risk of malignant mammary tumors in dogs spayed prior to their first heat cycle is a miniscule 0.05%. The risk increases to 8% for dogs spayed after one heat cycle and jumps to 26% in dogs spayed after their second heat cycle.
Diagnosis
It is very difficult to determine the type of tumor based on physical inspection. A biopsy or removal for histopathology is almost always needed to determine if the tumor is benign or malignant and to identify the type of tumor. Aggressive tumors may metastasize to the surrounding lymph nodes or to the lungs. A chest x-ray and physical inspection of the lymph nodes will help to determine if the tumor has already spread. Bloodwork and urinalysis as well as an abdominal ultrasound may also be recommended by your veterinarian.
Causation
Mammary tumors can be small, single nodules or large, aggressive, metastatic growths. With early detection and prompt treatment, many tumors can be successfully treated by your veterinarian. There are multiple types of mammary cancers in dogs. Approximately half of the mammary tumors in dogs are benign and the other half are malignant. The most common benign form of canine mammary tumors is actually a mixture of several different types of cells. This combination tumor in the dog is called a 'benign mixed mammary tumor' and contains glandular and connective tissue. Other benign tumors include complex adenomas, fibroadenomas, duct papillomas and simple adenomas.
Malignant mammary tumors include tubular adenocarcinomas, papillary adenocarcinomas, papillary cystic adenocarcinomas, solid carcinomas, anaplastic carcinomas, osteosarcomas, fibrosarcomas and malignant mixed tumors. Malignant mammary cancer can spread to the rest of the body through the release of individual cancer cells from the various tumors into the lymphatic system. The lymphatic system includes lymph vessels and lymph nodes. There are regional lymph nodes on both the right and left sides of the body under the front and rear legs. They are called the 'axillary' and 'inguinal' lymph nodes, respectively. New tumors may then form at these sites and then release more cells that go to other organs such as the lungs, liver or kidneys.
Treatments
AT-HOME CARE
Administer medications as prescribed by your veterinarian.
MEDICATIONS
Pain medication may be prescribed after surgery or radiation to aid in comfort of your pet. Examples of pain medications your veterinarian may prescribe include tramadol, gabapentin and Rimadyl.
While many medications are often administered for ‘off-label’ or 'extra-label' use in veterinary medicine, it is important to know that off- or extra- label use of a medication can only be done by a veterinarian when there are no other more appropriate medications for a particular pet's circumstances. Your veterinarian must also know all vitamins, supplements, medications etc. your pet is taking to help avoid complications. You must also be sure to follow all instructions provided by your vet carefully and consult your veterinarian with any questions or concerns if they arise.
MEDICAL PROCEDURES
The effectiveness of radiation therapy for mammary tumors in dogs has not been thoroughly researched and chemotherapy is typically reserved for advanced cases. Some anti-hormonal drug regimens are being tested in dogs. At this point in time, surgical removal of the tumors is typically the treatment of choice by most veterinarians.
SURGERY
Upon finding any mass within the mammary gland of a dog, surgical removal is typically recommended. If surgery is done early in the course of this disease, the cancer can be totally eliminated in over 50% of the cases with a malignant form of cancer. Sometimes a veterinarian may recommend that only the mass itself will be removed. Other times, taking into consideration how the cancer spreads, the mass and the rest of the mammary tissue and lymph nodes that drain the gland will be removed. With some types of tumors, especially sarcomas, complete removal is very difficult and many of these cases will have tumor regrowth at the site of the previously removed tumor. Your veterinarian will determine which option is best for your pet considering the type of growth and overall health of your dog.
SPECIALISTS
Most cases of mammary cancer will be referred to a specialist in veterinary oncology or surgery.
Cost Of Treatment
The cost of veterinary expenses varies widely for a variety of reasons, however, surgery to remove tumors may cost as much as $5000 or more depending on the size of the patient, health status and size of the tumor(s).
Recovery
Mammary cancer is a very common cancer, especially in female dogs that were spayed at maturity, and can often be successfully treated, if caught early.
Monitoring
Follow-up exams may be necessary depending on the type of tumor and the type of surgery undertaken. Your veterinarian will likely prescribe a surgical cone and exercise restrictions while your dog recovers from surgery to reduce the risk of injury to the incision site.
Prevention
Spaying female dogs before their second heat cycle greatly reduces their risk of developing mammary cancer. Regular physical exams may catch tumors while they are still very small.
Disclaimer
The information contained on this page is for educational purposes only. Treatment should only be provided under the advice of a veterinarian who has examined your pet under the laws applicable to your state of residence.